Funding for this research was provided by:
Shandong Key R&D Program (2015GSF118001, 2018GSF118058)
Shandong Medical Health Plan Program (2017WS192)
Received: 27 March 2019
Accepted: 24 June 2019
First Online: 4 July 2019
Ethics approval and consent to participate
: The study was approved by the ethics committee of our hospital and informed written consent was obtained from patients or guardians for participation and subsequent publication.
: Not applicable.
: The authors declare that they have no competing interests.